Protein base glues



Nov. 21, 1950 R. 5. PETERSON ETAL 2,530,780

PROTEIN BASE GLUES Filed Nov. 20, 1948 l0 Tofu] Assembly J7me (Minutes)m v w w w x m 3 IN VEN TORS RUSSELL GPETERSUN GERARD R. BRIE GER BYafla/ro M ATTORNEYS Patented Nov. 21, 1950 PROTEIN BASE GLUES Russell G.Peterson and Gerard R. Brieger, Ta-

coma, Wash, assignors to Balfour-Guthrie & Company Limited, Tacoma,Wash., a. corporation of Delaware Application November 20, 1948, SerialNo. 61,252

9 Claims.

Our invention relates to an improved hot press adhesive of the proteinbase type, and is particularly directed to an improvement in such a gluewhich enables joints of greatly increased strength to be made ascompared to such joints made with prior glues of the protein base type.Nevertheless the usual technique of applying the glue and heating andpressing the joint may be utilized with our glue.

While our glue is not restricted to use in the manufacture of plywoodfrom veneer sheets, it is especially useful for such purpose because itenables the veneer sheets to be laid up and to be pressed in theconventional fashion while insuring that the joints between the veneersheets in the final plywood product will be far superior in strength tothe joints usually made. In fact,

'almost invariably such a, joint made with our in proved glue isstronger than the maximum strength joint which could possibly beobtained by the use of protein base glues ordinarily used.

Glues of the protein base type which have been employed heretofore inthe manufacture of plywood of interior grade have been either seed base,blood base or blend base. Seed base glue incorporates comminuted seed,such as the meal or flour residue remaining after the oil has beenexpressed, or extracted by solvent action, from such seed products assoya beans, peanuts, cottonseed and the like, according to well knownmethods. Blood base glue employs principally blood or blood albumin asits base. Blend base glue has both comininuted seed and bloodingredients mixed in various proportions. The base may also incorporatecasein. To designate protein base incorporating blood, whether of theblood base Or of the blend base type as defined above, we shall use theterm blood content base in the following description, which sets uponthe application of heat and pressure to the joint. It is customary withany of these protein base glues to add to the base caustic alkali, lime,sodium silicate or other ingredients. Our invention constitutes animprovement particularly the blend base type of protein base glue,although it is also applicable to blood base glue, and hence is usefulgenerally in blood content base glues.

In the manufacture of plywood it is customary to prepare a batch of glueand to spread such glue on both sides of core stock veneer. In laying upthe veneer sheets preparatory to pressing them to form plywood, a faceply is first laid to form the bottom of the veneer staclz. Next, corestock with glue applied to both sides is laid crosswise of the faceveneer sheet, and on top of the core stock is laid either one or two drysheets of veneer, depending upon whether three-ply plywood or plywoodhaving a greater number of plies is bein made. If three-ply plywood isdesired, two dry face veneer sheets are laid on the core stock, and thenon the upper of these is laid another layer of core stock having glueapplied to both sides.

Thus dry veneer sheets and core stock having glue applied to both sidesare laid up alternately and with their grains crossed until a stack ofassembled plywood sheets sufiicient to constitute a load for amultiplaten hot press has been produced. Such presses usually have fromten to twenty openings, and may have more, and frequently more than oneplywood panel is pressed in each press opening, so that considerabletime is required to fabricate such a pile of stock. The time expended inthis operation should not be more than twelve minutes. When the veneersheets, or other elements to be joined, have been assembled for longerthan about ten minutes before being pressed, the bond of the resultingjoint is affected adversely. The longer the joint stands with glueapplied to it the greater is the deterioration of the glue bond in theset joint. Hence, in the use of usual hot press protein base glues tobond veneer in the manufacture of plywood, not appreciably more thantwelve minutes should elapse between the laying up of the lowermostplywood panel and the application of heat and pressure to such panelduring the glue-setting operation, in order to obtain a joint havingsufficient strength.

The principal object of our invention is to provide a hot press glue ofthe protein base type which can produce a'much stronger joint than ithas been possible heretofore to make with hot press protein base glues.More particularly, it is an object to enable a joint of greatly superiorstrength to be obtained as compared to such previous joints for anygiven elapsed time between the laying up of the parts to be joined andcompletion of the pressing operation.

As a corollary to the foregoing objects, it is a further object toproduce a joint at least equal in strength to those using hot pressprotein. base glue made heretofore, even when very much more timeelapses between the assembly of the parts to be joined and commencementof the pressing operation. As specific example, in order to obtainmaximum strength of joint with the usual hot press protein base glues,it would be necessar to press the elements between which the joint is tobe formed within approximately ten minutes after their assembly, asmentioned above, whereas a joint utilizing our improved glue would havesubstantially the same strength as such maximum strength prior artjoints if almost thirty minutes, or virtually three times as great aninterval, should elapse between assembly of the parts to be joined andapplication of. pressure in the pressing operation.

It is an additional object not only to provide a glue which will producea joint of much greater strength than those which could previously beobtained by the use of hot press protein base glues, but which willproduce a joint in which the decrease in its strength occasioned by theparts to be joined remaining assembled with glue between them prior tothe application of heat and pressure to them for any selected periodexceeding ten minutes will be less than where such prior glues are used.Such smaller decrease in joint strength for a given assembly time,coupled with the higher strength characteristics of our glue, enables ajoint of a strength at least equal to prior hot press protein base gluejoints to be secured by the use of our glue even though approximatelytwice the usual time should elapse between assembly of the parts beingjoined and the pressing operation.

By reason of the superior characteristics of our glue discussed above,joints of far greater strength than previously obtained by the use ofhot press protein base glues result when the same assembl timeand-technique are used as heretofore, and even if the assembly timeemployed is longer, such as where presses of. greater capacity areutilized, or more time for assembly is required for other reasons, thejoints secured. may nevertheless be stronger. than prior hot pressprotein base glue'joints.

The drawing is a graph representing the superior strength-assembly timecharacteristics of joints made with our glue as compared to conventionalhot press protein base glue joints.

We believe that a principal reason for the failure of hot press proteinbase glues incorporating blood to produce joints stronger than possibleheretofore has resulted from the blood not being in its most eficaciousform. We have found that this disadvantage can be overcome by adding toconventional blend base or blood base glues a small amount of aconditioning ingredient, believed to be in the nature of a solvent. Suchconditioner is an alkylbenzene, one species of benzenoid hydrocarbons,and specifically methylbenzene or a polymethylbenzene.

By polymethylbenzene is meant a chemical of the benzene series which iscomposed of the benzene ring in which two or more methyl radicals aresubstituted. Of the polymethylbenzenes those most suitable for our glueconditioner are the added despite the occurrence of a much greaterxylenes, because they are least expensive and readily available. Methylbenzene, that is, toluene also is suitable. We have found that thecommercial mixture of ortho, meta and para xylenes, commonly known asxylol, is quite satisfactory for our purpose. Other mixtures ofalkylbenzenes could also be used. It is important that the conditionerhave a boiling point higher than 100 centigrade. Thus, even toluene,having a boiling point of 110.6-110.8 Centigrade is quite satisfactoryfor use as our glue conditioner, while the xylenes, having an evenhigher boiling point of 1384M centigrade, are also suitable.

The conditioner preferably is incorporated in the glue with the otherliquid ingredients when they are blended with the dry glue baseingredients shortly before the glue is to be used. Alternatively,however, such conditioner may be sprayed into the dry glue base duringits manufacture in the same manner defoaming agents are customarilyincorporated with the glue base, and the conditioner may even be mixedwith the defoaming agent or agents and sprayed with them into the gluebase. Whether mixed with the glue base when other liquid ingredients areadded to it shortly before use of the glue, or sprayed into the gluebase, the amount of conditioner used should. be from one to five percentof the dry glue base by weight, and preferably about two percent.

A typical example of a glue of the blend base type incorporating ourconditioner and the method of its preparation follows:

Dry glue base Grams Soya bean flour 400 Soluble Whole blood solids 100Ingredients added when preparing glue for use Calcium hydroxide Causticsoda (sodium hydroxide) 37 Sodium silicate Carbon bisulfide-carbontetrachloride dope 3 Conditioner 10 Water 1900 Total 2&00

In the above formula the conditioner may, for example, be toluene, axylene, or xylol.

The procedure for preparing the dry glue base of mixedflour and solublewhole blood solids for use is first to stir such mixture into 1750 gramsof water until thoroughly mixed. Stir the calcium hydroxide into 100grams of water until thoroughly mixed in suspension, and add thissuspension to the flour and blood suspension. Add the caustic sodadissolved in 50 grams of Water to the combined flour, blood, and calciumglue, as described above, without conditioner added, a much weaker jointis obtained than when such glue with our conditioner added is used.Alternatively, a joint having a given strength may be secured by usingsuch a gluewith conditioner assembly time in fabrication of the jointthan in making the joint with glue devoid of our conditioner. Tests ofcomparative samples of joints made using such conditioned andunconditioned hot press protein base glues are illustrated in thedrawing. Curve A represents the results of tests on joints made invarious total assembly times utilizing lend base glue with xylolconditioner added, and curve B represents the results of tests onsimilar joints fabricated in various assembly times and using blend baseglue without conditioner, but made by the same technique.

Total assembly time as used in preparing the curves of the drawing isdefined as the total elapsed time between spreading the adhesive on thefirst core layer of a press load of plywood panels and application ofthe full pressure to the load of panels in the hot press. The totalassembly time which may be utilized is of considerable importance inpresent plywood manufacture. In the usual operation of manufacturingplywood by heating and pressing in a multiplaten hot plate press veneerto which hot press protein base glue has been applied, twelve minutesfrequently is not sufficient time in which to lay up and press theveneer sheets satisfactorily, and often more time is used, to thedetriment of the joint strength. An increase in assembly time fromtwelve minutes to the order of twenty minutes, readily afforded by theuse of our glue while still producing a joint of greater strength, isvery desirable.

Hot press protein base glue having a substantial blood contentapparently has a tendency to dry out and progressively lose its adhesivecharacter after it has been spread and before heat and pressure isapplied to the parts to be joined to such an extent as to impair itsthermoplastic properties to a greater or lesser degree when subjected toheat and pressure. Where hot press protein base glue of conventionaltype is employed in making plywood a decided difference in the strengthcharacteristics of the plywood panels first laid up and those last laidup in a press load is very noticeable, resulting from the lower strengthof the joint occasioned by the appreciable difference in time betweenthe application of the glue to the lower panel core layer and to theupper panel core layer in such a press load. Where an unexpected delayoccurs, therefore, the strength of the bottom panel or panels in a pressload frequently is substandard, whereas such occurrence would almostinvariably be avoided where our conditioned glue is employed, because ofthe generally higher strength characteristics of its joints andespecially because of the smaller decrease in strength of its jointsresulting from an increase in assembly time.

We claim as our invention:

1. An adhesive composition comprising a base 45 incorporating bloodmaterial of the group consisting of whole blood solids and bloodalbumin,

and a conditioner of the group consisting of toluene andpolymethylbenzenes in an amount by weight of l to 5% of said base.

2. The adhesive composition defined in claim 1, including a conditionerin an amount by weight of about 2% of the base.

3. The adhesive composition defined in claim 1, in which the conditioneris toluene.

4. The adhesive composition defined in claim 1, in which the conditioneris of the group consisting of xylenes.

5. The adhesive composition defined in claim 1, in which the baseincludes, by weight, a major proportion of comminuted seed and a minorproportion of blood material.

6. The adhesive composition defined in claim 5, in which the baseincludes, by weight, about comminuted seed and about 20% blood material.

7. The adhesive composition defined in claim 6, including a conditionerin an amount by weight of about 2% of the base.

8. An adhesive composition comprising a base including, by weight, about80% comminuted seed and about 20% blood material of the group consistingof whole blood solids and blood albumin, and a conditioner of the groupconsisting of toluene and Xylenes in an amount by weight of about 2% ofsaid base. i

9. An adhesive composition comprising a base incorporating bloodmaterial of the group consisting of Whole blood solids and bloodalbumin, and a conditioner of the group consisting of toluene andpolymethylbenzenes in an amount by weight of about 10% of said bloodmaterial.

RUSSELL G. PETERSON. GERARD R1. BRIEGER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,392,849 Plauson Oct. 4, 19212,014,167 Bowen Sept. 10, 1935

1. AN ADHESIVE COMPOSITION COMPRISING A BASE INCORPORATING BLOODMATERIAL OF THE GROUP CONSISTING OF WHOLE BLOOD SOLIDS AND BLOODALBUMIN, AND A CONDITIONER OF THE GROUP CONSISTING OF TOLUENE ANDPOLYMETHYLBENZENES IN AN AMOUNT BY WEIGHT OF 1 TO 5% OF SAID BASE.